Money and class

Money is associated with class. The more money that you have the higher up in the social ladder that you are. I think this is why in music predominatly associated with a working class (like rap, pop, country, blues, etc) there are so many referrences to money. The lower classes realize that money equals class, and they aspire to it. While the higher classes (represented as you stated with classical music) never mention money. The higher classes feel that they dont need to aspire to what they already have.